The referenced application Ser. No. 06/930,280, filed Nov. 12, 1986, assigned to the assignee of the present application, and the disclosure of which is hereby incorporated by reference, now U.S. Pat. No. 4,747,624, describes a connection arrangement to connect two pipes, particularly for conveying hot fluids, and especially exhaust gases from internal combustion engines, in which one of the pipes has an end portion facing the end portion of the other, the connection arrangement connecting the pipes together while permitting relative movement of the pipes in axial, lateral, and twist or torsion directions. Special arrangements are provided to prevent escape of fluids to ambient space which includes a sealing pillow located in a ring chamber in which the sealing pillow has a sealing membrane embedded therein, the sealing membrane extending over the entire radial region of the space or chamber. The sealing membrane is made of a temperature-resistant and corrosion-resistant material.
The sealing cushion may be a ceramic or metal structure formed of fibers or matted material which may be woven, knitted, felted or otherwise shaped, for example of compressed fibers or fiber particles. The ring chamber is formed by wall elements which may include abutments formed, for example, by snap rings or the like, to maintain axial positioning of the respective elements. In operation, the sealing chambers and the sealing membranes, which form unitary combinations, may be radially compressed, and it has been found that such radial compression may lead to loss of sealing effectiveness or to leakages. The seal has the advantage that it is movable in torsion or twist. This, however, can become excessive and substantial freedom in torsional or twisting movement is undesirable for many applications, even if portions of the sealing cushions are retained in projecting wall portions secured to, or forming part of the respective pipe elements. In operation, and particularly when subjected to hot exhaust gases, leakages may occur and the sealing cushions, particularly upon settling, may slip within the overal arrangement.
German Pat. No. 22 22 355 discloses a flexible connection of two pipe ends in which a bellows or corrugated tube element forms a primary seal. A secondary seal is formed by a ring plate secured to one of the pipe elements, and slidable with respect to a flange surface provided on the other pipe element. There are no sealing cushions, and a primary seal is provided only by the bellows.